Thanks for the links Adrians,
I don't know if i'll make a such mod, i think i will place the wattmeter at the half height of the handlebar, by this way once the scooter Folded the wattmeter will be more protected. I am stell thinking about it.
Yesterday i made new tests with my 3s 2200Battery. Even with this low capacity the power was really good, in fact as good as the 4s 5000, that because i didn't use full power on the 4S.
so its decided, i will use an 3S 6000mAh, as you said Adrian, i will have less power than with an 4s battery, but with an 3s i am allready at the max capacity of the motor, so more power from the battery should only by usefull for burning the motor
then i made an test in real condition : going from my garage to my home, its about 1Km. 4 road to cross. At each acceleration, i helped the motor with the foot. Finally it perfectly fits with what i needed : an light electric scooter with a small motor just enough to maintain the speed.
the speed was good, on flat i think i am about 20-25Kph. and finally the motor was not hot. on flat at constant speed it pulls between 100 and 200Watts.
now i have to pass all the wire in the scooter, make Hoods for protecting the battery, the motor and the chain. And Finally make an system to Tighten the chain.
i'll make new pictures.
and then, i'll can go to work with my scooter by taking the subway